Difference between LS1, LS2, HG

If the firmware version is 1.xx then you have a ppc-based-Linkstation (LS1,HG), if it is 2.xx it is an LS2 (mips).
all LinkStations except the LS1 have autosensing, so no switch for changing the LAN-Port is there.

Rear View

LS2 and HG

LS1

The powerpc-hdhlan (LS1) LinkStation can also be identified by the presence of a crossover switch located at the rear of the unit; the mipsel-hdhlan (LS2) and powerpc-hdhglan (HG) LinkStations do not have a crossover switch as they are auto-switching.